From this question I learned that Google App Engine does not currently support SSL on \"custom domains\" (at least not as of June 2010, when that question was asked).
<You can get SSL to work on your custom domain hosted on AppEngine, however you need to run a reverse proxy that can modify the host header to do so. If you want to setup a reverse proxy yourself, you can do so following these instructions:
http://radomirml.com/2011/01/30/reverse-proxy-for-gae-application-using-nginx-and-ssl
Alternatively, you can use a reverse proxy service like CloudFlare. The process of getting SSL to work with an appspot.com domain is documented on the CloudFlare Blog:
http://blog.cloudflare.com/ssl-on-custom-domains-for-appengine-and-other
A few days ago it comes into tests.
Here's a HOWTO I wrote up explaining how to do SSL on your custom domain using CloudFlare:
http://blorn.com/post/20185054195/ssl-for-your-domain-on-google-app-engine
Since Sdk 1.7.0, released at Google I/O, developers can serve their applications via HTTPS on custom domains using both SNI (Server Name Indication) and VIP (Virtual Ip) based SSL.
You can use wwwizer.com - it is a reverse proxy service with SSL.
You get an individual IP and it is showing your app both on http and https ports. It is cheaper and easier than hosting the whole server yourself.
This is my service, so, yes, this is blatant advertising :-)
All secure traffic with Google App Engine must be served from your appspot.com domain (https://your-app-id.appspot.com). If you are serving your app off of a Google Apps domain, you must direct all secure traffic through your app's appspot domain.
This is what is written in google app engine documentation. That means. SSL is supported on appspot.com domain